FBO render to texture using VBO

This example uses immediate mode to draw triangles to the texture but I'd like to use VBO. I'm very new to OpenGL and have my rendering working using VBO but I don't know how to replace the random triangle rendering in this tutorial with DrawElements using VBO.

It looks like you FBO render is only rendering the red channel but I don't know why. You can confirm this by clearing the backgroundto with say white and
see what clear colour appears when you render the FBO texture.

Just some other notes

Usually your

GL.PushMatrix(); GL.PopMatrix();
are around any changes to the matrices not after you change them. The idea is to also know what state the matrices are in.

Check you calls to glViewport since this effect where things are drawn on the window. Also check calls GL.MatrixMode to see what matrix is being set to identity matrix - I assume it is the projection matrix since
I think it need to be set to identity as well to render a whole screenquad (I am a bit vague because I have been using shaders to do this for so long I forget exactly how the old fixed pipeline works).